What’s Hot in Clots – February 2023

Key Updates in Thrombosis

Table of Contents
  1. Not meeting non-inferiority: The case of low-intensity versus standard warfarin anticoagulation after On-X mechanical mitral valve replacement
  2. Aspirin prophylaxis for venous thrombosis: More confusing than coffee and cardiovascular diseases!
  3. AHA Scientific Statement on surgical management and mechanical circulatory support for PE
  4. Recurrent VTE during treatment with rivaroxaban: Adding aspirin or switching to vitamin-K antagonists?

Not meeting non-inferiority: The case of low-intensity versus standard warfarin anticoagulation after On-X mechanical mitral valve replacement

In a randomized trial of 401 patients who underwent On-X mechanical mitral valve replacement, all of whom received low-dose aspirin, there was no significant difference between low-intensity (INR target 2-2.5) and regular (INR target 2.5-3.5) warfarin therapy for the primary outcome – the sum of the linearized rates of thromboembolism, valve thrombosis, and bleeding events. Although the event rates were comparable in the two groups (11.9% vs. 12.0% per patient-years of follow-up), the upper bound confidence interval of absolute difference crossed the non-inferiority margin of 1.5%. In the recent ACC/AHA valve guidelines, co-administration of aspirin is not necessary in all patients. Therefore, the future of the On-X valve (which mandates coexisting aspirin) for patients requiring mitral mechanical valve is uncertain. Learn more!

Aspirin prophylaxis for venous thrombosis: More confusing than coffee and cardiovascular diseases!

This is only slightly better than random medical news, where various foods and drinks are shown to correlate with either increased or decreased cardiovascular risk every other day! The saga continues regarding the use of aspirin in prevention of venous thrombosis after orthopedic surgery. In this RCT, adult patients with extremity fractures requiring surgery, or with pelvic/acetabular fractures, were randomized to aspirin 81 mg bid or enoxaparin 30 mg bid. There was no significant difference between the two groups for the primary outcome of 90-day all-cause mortality (P<0.001 for a noninferiority), or for bleeding events, although—similar to some prior trials—there were more DVTs in the aspirin arm. Learn more!

AHA Scientific Statement on surgical management and mechanical circulatory support for PE

In this AHA Scientific Statement, the authors share a historical perspective, anesthesia considerations, surgical techniques, and outcomes of embolectomy, venoarterial ECMO, and percutaneous right ventricular support devices. Learn more!

Recurrent VTE during treatment with rivaroxaban: Adding aspirin or switching to vitamin-K antagonists?

A pilot trial of 58 patients with recurrent VTE [who were treated with rivaroxaban] were randomized to either continued treatment with rivaroxaban 20 mg daily plus addition of aspirin or switched from rivaroxaban to acenocoumarol. There were three thrombotic events and five minor bleeding events at 90-day follow-up, all in the acenocoumarol group. One major nonfatal bleeding event occurred in the rivaroxaban group. Learn more!

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Behnood Bikdeli, MD, MS 

Cardiologist, Section of Vascular Medicine, Division of Cardiovascular Medicine, Brigham and Women’s Hospital 

Investigator, Thrombosis Research Group, Division of Cardiovascular Medicine, Brigham and Women’s Hospital 

Instructor, Harvard Medical School 

Investigator, Yale/ YNHH Center for Outcomes Research and Evaluation, Yale School of Medicine 

Investigator, Cardiovascular Research Foundation 

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